Rf, Thermal and Structural Analysis of a High Power Cw Rf Window

The present Jefferson Lab Free Electron Laser window requirements were used to develop a RF window design. These requirements include 1.497 GHz as the design frequency, and require the window to pass higher modes that originate in the cavity. The VSWR should be less than 1.1:1 at the design frequency and no greater than 1.5:1 at frequencies up to 2.2 GHz. The finite element method was used with the same node and element connectivity for the RF, thermal, and structural models enabling loads to be passed directly. Dielectric losses from the RF analysis were passed directly to the thermal model as heat loads within the window. The temperature distribution is calculated and passed directly to the structural model. The broadband VSWR requirements of the window are achieved by varying appropriate geometry parameters. Maintaining these parameters at reasonable minimum dimensions provides for up to three atmospheres of pressure differential. The high thermal conductivity of BeO and a cooling channel located around the window edge enables efficient heat removal from the window and therefore high power throughput, greater than 100 kW.